The first IS an identity, the second isn't. Are you supposed to test if the equation is an identity?

a) There is nothing to do on the LHS, so go to the RHS and simplify:

(x + 1)(x - 1) + 2(x + 1) - 3

x^2 - 1 + 2x + 2 - 3

x^2 + 2x + (-1 + 2 - 3)

x^2 + 2x - 2

Since the LHS and the RHS are identical, this equation is an identity.

b) Again, nothing to do on the LHS, so go to the RHS:

7(x + 1)(x - 2)

7(x^2 - x - 2)

7x^2 - 7x - 14

The LHS and RHS are not the same, so this is not an identity, but a "conditional equation."

-Dan